I claim PIP, and am **** years old. Can I also get pension credit?

That will depend on your circumstances. More information is needed for anyone to be able to advise you.
Do you live alone or with a partner? If with a partner are they state pension age? 

If it's just the 2 of you at home then claiming Severe disability Premium is possible which is paid as part of pension credit. Whether there's any entitlement will depend on your joint circumstances. Best thing to do is use the benefits calculator i linked above and put both your details into it.

calcotti said:

If nobody receives Carers Allowance or the carer element of UC for looking after either of you and there is nobody else living with you then if your weekly income (excluding the PIP) is less than £417.50 then you will have entitlement to some PC.

There is a Pension Credit calculator 
https://www.gov.uk/pension-credit-calculator

Are you claiming Council Tax Reduction from your council?

The above figure excludes two possible claims for Carers Allowance with each caring for the other. Though nothing would be paid for that claim an underlying entitlement will exist that is worth another £77.70 a week taking the amount of Pension Credit max to £495.20 a week. If the net income excluding PIP and AA is below that figure the Pension Service will make up the difference.

I note that they are receiving private pensions/annuities and I presume that they are not paying tax on them. If they are then if there is a increase or decrease each time the payment is made they must inform the Pension Service or risk being investigated for failing to report a change. That change is for 1p and more up or down.

Additionally there is no need to claim CTS as with any Pension Credit award there will be no Council Tax to pay.